Most seed planters as currently manufactured utilize a pair of rotatively mounted disks that substantially contact each other where the disks enter the ground and diverge rearwardly and upwardly as they exit the ground, thereby forming a V-shaped furrow in the ground into which seed is deposited. These disks are supported on a frame which is connected to a tool bar by means of a parallel linkage which allows vertical motion of the frame as the planter is drawn across a field. The planter frame is supported by means of a pair of gauge wheels which are pivotally mounted to the frame, but which are incrementally limited in their movement relative to the furrow disks, so as to control the depth of penetration of the disks into the earth. The axis of each gauge wheel is positioned immediately aft of the axis of each furrow disk unit with the gauge wheel tires riding adjacent and pressing against the furrow disks. In this manner the gauge wheels also function to clean moist, sticky soil from the disks. After a period of time, the bore of the gauge wheel arm hub and the gauge wheel arm pivot shaft become worn, allowing the gauge wheel tire to shift away from the furrow disks, rendering the gauge wheels incapable of cleaning the disks and allowing mud and other debris from building up within the gauge wheel assembly.
A later version of the prior art design incorporates the use of a bushing over the gauge wheel arm shaft and a larger bore in the gauge wheel arm hub. This improves durability by providing a larger bearing area. It also prevents wear to the pivot shaft which is an integral part of the planter frame. Although an improvement, the addition of the bushing has not overcome the basic problem of radial looseness due to wear between the pivot parts.